Printing telegraphy



Patented Mar. 29, 1938 UNITED STATES PATENT OFFICE PRINTING TELEGRAPHYApplication March 27, 1935, Serial No. 13,296 In Germany March 27, 193413 Claims.

Our invention relates toprinting telegraphy, and more particularly to anarrangement for dialling in printing telegraph exchange systems.

In printing telegraph exchange systems, in

which regenerative repeaters are employed, the transmission of thedialling impulses presents difiiculties, since the dial. switchtransmits a train of impulses differing from that of the printingtelegraph, so that a mutilation of the dialling impulses occurs whentransmitting the dialling impulses through a regenerative repeater.

To eliminate the above difiiculties it has already been proposed toprovide by-pass devices for the regenerative repeaters that areeffective during the transmission of the dialling impulses and transmitdirectly the dialling impulses by bypassing the regenerative repeater.For the control of these by-pass devices in accordance with theestablishing of connections, particular switch- :70 ing means are,however, necessary which cannot be employed in all cases or which atleast unnecessarily complicate the exchange equipment.

The present invention has for its object to provide an arrangement fordialling in printing telegraph exchange systems whereby theabove-mentioned difficulties are eliminated and is based on the facthitherto unknown that it is more convenient to retain the regenerativerepeater unaltered in the lines or circuits and to efiect in this casethe dialling in such a manner as to attain a satisfactory transmissionof the dialling impulses beyond the regenerative repeater and, undercircumstances, even a correction of the dialling impulses by means ofthe repeaters. This may be accomplished according to the invention byadapting the speed of the dial switch to the speed of rotation of aprinting telegraph transmitter.

This inventive idea may be realizedin various ways. By the use of anindependent dial switch, i. e., of a dial switch which is as usualindependent of the printing telegraph, it is possible to reduce thespeed of running down of the dial switch to such an extent that theperiod of the dialling impulses produced is substantially equal to thelength of a complete code impulse combination. If the limiting values ofthe speed which depend upon the manufacturing tolerances of the dialswitches aretaken at the same time into consideration it is necessarythat the period of the dialling impulses in the case .of the highestpermissible speed should last at least as long as a complete codeimpulse combination.

Another possibility of realizing the invention consists in the fact thatthe speed of. the dial switch is controlled by the printing telegraphap- (Cl. PIS-75) paratus, the control being effected by the electricalor mechanical method as the case may be. For instance, the running downof the dial switch may be retarded by an escapement which may bereleased by the impulses produced by an electromagnet controlled by theprinting telegraph apparatus. Such an escapement may, however, be madeconditional by the mechanical method upon parts of the printingtelegraph apparatus moved in rhythm with the normal telegraph signals.This may be accomplished in a particularly convenient manner by causingthe dial switch tobe operated by the motor of the printing telegraph. Tothis end, a control member may, for instance, be provided on thetransmitter shaft or on a shaftcoupled with the transmitter shaft. Thecontrol member then operates the dialling impulse contact and its numberof revolutions is limited by correspondingly ad-' justed devices inaccordance with the angular position of the dial switch pulled round.

Further details of the invention will be apparent from the followingdescription taken in connection with the drawing. Fig. 1 shows variousgraphic representations of impulses for illustrating the variation ofthe impulse periods of a standard dial switch as is required accordingto the invention, whereas Fig. 2 showsan embodiment of a dial switchcontrolled mechanically by the printing telegraph.

The upper portion a of Fig. 1 illustrates in diagrammatic form thesignal units of a normal fiveunit combination together with the startingimpulse A and the stop impulse S. The five characteristic impulse unitswhich have normally a length of 22 ms. each lie between the starting andthe stop impulse which also have the same length, so that the durationof a complete code impulse. combination amounts to 154 ms.

The dial switch developed for use in connection with telephony and whichis also employed in the same form in automatic printing telegraphexchange systems has upon an average a running down period of one secondper ten dialling impulses. The prescribed value of a period consistingof a current break and make consequently amounts to 100 ms, see portionb of Fig. 1. In this case the impulse ratio is chosen in such a mannerthat the current is off during 38.5 ms. and the current is on during61.5 ms. This off to-on ratio is indicated in portion b by the longcross line. The tolerances ilor the departure from this normal oiT-to-onratio amount in this case to i as is shown by the short cross linesdrawn close tothe long cross line.

The dial switch has, however, very considerable speed tolerances owingto the manufacture and cheapness thereof. The value of ms. for eachperiod of the current impulses indicated in portion b represents only amean value. The period in the case of the greatest running down speedpermissible in accordance with the tolerance may actually amount to 75ms. (portion 0), whereas the complete running down of the dial switchwith the lowest speed permissible according to the tolerance lasts 1.6sec., 1. e., the current impulse period amounts to 160 ms, (portion d).Accordingly, the shortest duration of a current-off period amounts to 29ms. (portion 0) and the longest duration of such period or break amountsto 61.5 ms. (portion d).

If these impulse periods according to the portions 17, c, and d arecompare-d with the length of a complete code impulse combinationaccording to portion a it will be apparent that a normal dial switchcannot cooperate in a perfect manner with a printing telegraph apparatusor with a regenerative repeater, for in the case of a rapid dial switchaccording to portion a a rotation of the regenerative repeater (154 ms.)would correspond approximately to two periods ms.) and in the case of aslow dial switch according to portion at not even to a complete periodms.) In this case, however, it must be above all considered that owingto the nature of the regenerative repeater additional variations of thedialling impulses may occur, i. e., shortenings or lengthenings by atmost 22 ms., so that the current break might be suppressed, forinstance, in the case of a rapid dial switch according to portion 0.

According to the invention the running down speed of the dial switchshould, therefore, be adapted to the length of the code impulsecombination, for instance to 154 ms. in the example illustrated byportion a. of Fig. 1. The most favorable adaptation may be attained ifthe current impulse period of the dial switch for the highest runningdown speed permissible according to the tolerance is at least equal tothe length of a complete code impulse combination (assumed above as 154ms.). In the case of the percentages so far considered for the toleranceof the running down speed a current impulse period of 214 ms. with abreak duration of 82.5 and a make duration of 131.5 ms. results as meanvalue, provided that the usual break-to-make ratio is taken as a basis(portion e). The dialling of the most rapid dial switch coincides inthis case with the dialling of the normally dimensioned slowest dialswitch (portion 61). The impulse period of the slowest dial switchdimensioned according to the invention amounts to 342 ms. with a break(current-off) period of 132 ms. and a make (current-on) period of 210'ms. (portion 1).

If this normal break-to-make ratio is taken into consideration a furtherdifiiculty, however, results as will be apparent in comparing thegraphic representation with the one at a. In this case the break may beso long that it falls within the stop impulse S of the code impulsecombination, so that it may happen that the shaft of the regenerativerepeater is not stopped at all, thus causing a wrong transmission of thedialling impulse.

In order to eliminate this fault the break-tomake ratio must, therefore,be also chosen quite otherwise than is the case with the dial switcheshitherto known, that is to say, the longest possible break during therunning down of the dial switch inclusive of a certain allowance forsafety should not be greater than 132 ms. (duration of a code impulsecombination without stop impulse). The portions e, h and i of Fig. 1show a break-to-make ratio which may be considered suitable in view ofthe above-mentioned conditions. The portion it represents in this caseagain the mean value with a current impulse period of 214 ms. and with abreak-to-make ratio of 66 ms. for the current break and 148 ms. for thecurrent make. For the most'rapid dial switch the break-to-make ratioamounts to 49:111 ms. for a period of 160 ms. (portion 9), whereas forthe slowest permissible dial switch the impulse period is equal to 342ms. with a break-to-make ratio of 106:326 ms. (portion i). Naturally,these figures represent only approximative values which may be varieddepending upon the particular requirements.

The above-mentioned variation of the normal running down speed of a dialswitch may be attained in some cases by another adjustment of thestandard dial switches. If this is not possible it will be, as a rule,sufficient to effect a simple change in the dimensions, for instance anincrease in the flywheel weight of the regulator or a change in theforce of tension of the spring acting on the flywheel weight in order toobtain the desired dialling.

Fig. 2 shows an embodiment of a dial switch which is not drivenindependently of the printing telegraph as the dial switches so fardescribed, but is controlled by the printing telegraph itself.

It is assumed that the drive of the dial switch is effected by thetransmitter shaft of the printing telegraph. To this end, thetransmitter shaft is provided with a slip coupling (not shown) and isassociated with the shaft l of the dial switch by means of the slipcoupling. The shaft I carries a cam disc 2 as control member foractuating the impulse contact 3. When the motor of the printingtelegraph is running the shaft l is, therefore, continuously under theeffect of the revolving transmitter shaft, the shaft I being, however,held at rest when the lug 5 of the disc 4 mounted on. the shaft I faces,as disclosed in Fig. 2, the end of the lock lever 6. The lock lever B isrigidly mounted on the shaft 7, to the front end of which the dialswitch 8 is secured. The escapement wheel 9 cooperating with the pawlIll and a worm wheel II firmly secured to the escapement wheel 9 areloosely mounted on the shaft 1. The worm wheel ll meshes with the worml2 mounted on the shaft I.

If the dial switch is pulled round in. the usual manner by hand the locklever 6 rotates and the pawl l0 slides over a number of teeth of theescapement wheel 9 corresponding to the dialled number. Upon therotation of the lock lever B the lug 5 is released therefrom so that theshaft l begins to rotate. After the shaft has rotated a given angle thelug I8 is, however, firmly held again by the lever l3 which is coupledwith the shaft 1 of the dial switch 8 by means of a weak frictioncoupling 14 and which moves away from its stop l5 when the dial switchis pulled round. The shaft I makes, therefore, only a preparatorymovement when the dial switch is pulled round which movement, however,does not yet bring about an actuation of the contact 3.

Only when the dial switch is released the shaft 1 begins to rotate inthe opposite direction under the action of the spring l6 and the leverI3 is brought back to its normal position so that the lug I8 is alsobrought out of engagement with the lever l3 and the shaft I is againfree to rotate. Upon every complete revolution of the shaft the impulsecontact 3 opens for a given time corresponding to the recess of the disc2 so that a number of impulses are produced corresponding to the numberof the possible revolutions of the shaft I. The shaft l comes to rest assoon as the lock lever 6 together with the dial switch 8 reaches itsnormal position in which the lug is again locked.

In order to prevent undesirable controls of the printing telegraphexchange devices it has been found necessary to lock the dial switch aslong as the circuit closing key is not pressed, i. e., as long as thedriving motor of the printing telegraph is not running. This locking isbrought about in the arrangement shown in Fig. 2 by the fact that theend of an extension I! of the pawl Iii faces in the position of rest alug I8 arranged on the disc 4. If the dial switch is to be pulled roundthe pawl ill must at first pass over the teeth of the escapement wheel9, i. e., the extension ll must move towards the disc 4. This movementis, however, not possible if the motor and, consequently, also the disc4 are at rest, for in this case the lug l8 prevents a rotation of thepawl iii.

A further measure of safety consists in the provision of the cam disc l9and the contact 20. It may happen that the dial switch in the case of anunexpected disconnection of the motor-for instance by means of anengaged signal coming from the exchange-comes to rest in another than inthe position of rest. in such a manner that the contact 20 is openedowing to the design of the cam disc l9 only in the normal position ofthe dial switch, otherwise the contact 20 is closed. This contactmaintains, for instance, the motor cut-in relay in a local circuit in anenergized state or bridges the contacts of the motor cut-in relay.

In the above-described arrangement it is pre-' supposed,,as will beapparent from the drawing, that the break time of the impulsetransmitting contact 3 is shorter than the make time, and accordinglythe recess of the cam disc 2 takes up less than the half of theperiphery thereof. It is, of course, possible to adjust other impulseratios with longer break duration, if a smaller portion of the rotationis interposed between the limiting points of the levers 6 and 13 by acorresponding modification of the construction. Instead of theabovementioned friction coupling it is, of course, possible to use aclaw coupling which must be then engaged and disengaged by the levers 6and IS. The adjustment is then to be efiected in such a manner that whenpulling round the dial switch there is no position in which both leversrelease the disc 4.

The impulse transmitter shown in Fig. 2 is designed in such a mannerthat it is possible to combine the impulse transmitter with a printingtelegraph to form a unit. This arrangement has the advantage that thecase for the dial switch, which is, as a rule, arranged at one side ofthe usual printing telegraph, may be dispensed with.

We claim as our invention:-

1. In a printing telegraph, the combination of a number impulse-producerprovided with a rotary member having a connection for operating suchmember by a member of the printing telegraph proper, saidimpulse-producer further including switch means actuated by said rotarymember, the latter being constructed to adapt the impulse ratio of thecurrent impulses to the length This may be avoided I of a telegraphiccode combination of the printing telegraph. transmitter, in such amanner that the period of the stop impulse of a telegraphic codecombination will occur during an interruption of the number current, andmeans controlling the rotary member to adapt its rotary speed to thetelegraphing speed of the transmitter.

2. A device according to claim 1, in which the parts are so proportionedthat the length of the impulses produced by the impulse-producer will beapproximately equal to the length of a telegraphic code combination.

6. A device according to claim 1, in which the parts are soproportion-ed that at the highest permissible rotary speed the period ofthe number impulses produced will be at least equal to the length of acomplete telegraphic code combination.

4. A device according to claim 1, in which the parts are so proportionedthat the longest permissible interruption of the current controlled bysaid impulse producer will be at the most equal to the length of atelegraphic code combination exclusively of the stop impulse.

5. A device according to claim 1, in which the parts are so proportionedthat the longest permissible current impulse controlled by saidimpulse-producer will beat the most equal to the length of a telegraphiccode combination exclusively of the stop impulse.

6. In a printing telegraph, the combination of a telegraph transmitter,a number impulse-producer, means for operating said numberimpulseproducer by a member of said telegraph transmitter, andadjustable control means for controlling the extent of operation of saidmeans for operating said number impulse-producer.

7. In a printing telegraph, the combination of a rotary member having aconnection for operating such member by a member of the printingtelegraph proper, switch means co-operating with said rotary member toproduce signal impulses, a dialling member, and means controlled by suchdialling member for permitting or arresting the operation of said rotarymember.

8. A device according to claim 7, in which the dialling member controlstwo pawls arranged to arrest the rotary member at two different pointsof its motion.

9. A device according to claim 7, in which there is provided, inconjunction with the dialling member, means for releasing said rotarymember for a number of revolutions corresponding to the dialled number.

10. A device according to claim 7, provided with means for blocking theoperation of the dialling member in the event that the said member ofthe printing telegraph proper is not operating.

11. A device according to claim 7, provided with means for permittingthe drive of the telegraphic transmitter to be interrupted only when thedialling member is in its initial position.

12. A device according to claim 7, provided with a switch and meansoperatively connected with the dialling member for opening said switchonly when said member is in its initial position.

13. A device according to claim 7, provided with a switch which whenclosed causes the operation of the telegraph transmitter, and meansoperatively connected with the dialling member for closing said switchwhenever the dialling member is out of its initial position.

EI-IRHARD ROSSBERG. HERBERT WiisTENEY.

